1. Field
The following description relates to computer graphics, and more particularly, to progressive mesh decoding algorithms used to represent a three-dimensional model in computer graphics and methods using the same.
2. Description of the Related Art
A polygonal mesh is widely used as a method of representing a three-dimensional model is in computer graphics. Such a polygonal mesh is used to define a shape of a three-dimensional model to be represented, and a triangle mesh is mainly used as the polygonal mesh. The triangle mesh refers to a representation scheme, in which a three-dimensional model having an irregular shape is decomposed into a plurality of triangular facets to represent the shape of the three-dimensional model, or refers to a graphic image represented through this representation scheme. According to the triangle mesh, geometry information of vertices forming a triangle and connectivity information of connecting the vertices are used to represent a model, and thus the representation of a three-dimensional model requires much more data as compared to when representing a two dimensional model having a regular shape.
In compressing or encoding a triangular mesh, a scheme of encoding a triangular mesh having a simple resolution, that is, a scheme of encoding vertices and connectivity information between the vertices has been suggested. However, such an encoding scheme may easily be affected by time delay or transmission error occurring in a network transmission. In addition, in a graphic application device for representing a three-dimensional model by employing such a simple resolution mesh, a three-dimensional image having various resolutions is not represented in a rapid manner.
As an alternative to improve such drawbacks of the simple resolution mesh, a progressive mesh encoding algorithm also called a progressive mesh compression algorithm has been suggested. For example, where the progressive mesh algorithm is used, a mesh having a desired resolution is reconstructed by increasing the resolution from a base mesh having the lowest resolution by one level at a time. In a graphic application device employing such a is progressive mesh encoding algorithm, a remote object is schematically represented at a low resolution and a close object is represented in detail at a high resolution.
However, according to the progressive mesh algorithm capable of obtaining a three-dimensional image with various resolutions, larger amounts of data need to be encoded as compared to the single resolution mesh algorithm. The amount of encoding data is directly proportional to the resolution level supported by the progressive mesh algorithm. Even though network bandwidths, data transmission speeds and capacities of storage medium are continuously increasing, this increase of data causes a difficulty in encoding, transmitting, storing and decoding the data. In this regard, a progressive mesh decoding method capable of reducing the amount of mesh data generated through an encoding algorithm and efficiently reconstructing a three-dimensional image having various resolutions is required.
In addition, the reconstructed mesh resolution needs to be changed in a graphic application device in a flexible and rapid manner. For example, if the position of a camera or object changes, the resolution of a three-dimensional image being displayed needs to be increased or decreased rapidly according to the direction of change. In this regard, a progressive mesh decoding method capable of reconstructing a three-dimensional image having a desired resolution in a flexible and rapid manner is required.